1. Field of the Invention
The present invention relates to an image recording apparatus comprising a linear encoder.
2. Discussion of Related Art
There has conventionally been known an image recording apparatus, such as an ink-jet printer, which forms an image on a recording medium such as a recording sheet and which has a structure to record the image on the recording medium by alternately moving a carriage on which a recording head is mounted in a main scanning direction and the recording medium in a sub scanning direction. In addition, there has generally been known that the above-described image recording apparatus is equipped with a linear encoder so as to detect a position of the carriage in the main scanning direction. More specifically, the linear encoder comprises a belt-like linear scale which has a plurality of detectable portions (such as marks or slits) arranged at a predetermined pitch and which is provided along the main scanning direction. The linear encoder also comprises a detector, mounted on the carriage, which detects each of the detectable portions (strictly speaking, a part of said plurality of the detectable portions at a time) so as to detect a position of the carriage, namely, to detect a position of the recording head mounted on the carriage.
In the thus constructed image recording apparatus, the linear scale is provided along the main scanning direction such that both end portions of the linear scale are supported. However, the detection accuracy of the position of the carriage lowers as the linear scale is slackened by gravity.
Therefore, as being disclosed in JP-A-2004-160871 for instance, there has been proposed an image recording apparatus which comprises a plate spring (i.e., a leaf spring or a flat spring) that supports one end of the linear scale. In the image recording apparatus, the plate spring is fixed on one of left and right side plates of a box-like main body chassis. One end of the linear scale is supported by the plate spring and the other end thereof is supported by the other side plate of the main chassis. Owing to the arrangement, the linear scale, provided along the main scanning direction, is appropriately tensioned so as to prevent the slackness of the linear scale.